1. Field of the Invention
This invention relates generally to filtration, and, more particularly, to a filtering means for the removal of contaminants from a fluid flow.
2. Description of the Related Art
A very common requirement of several industries, such as chemical and biological manufacturing, food processing, ore processing, health care facilities, and water and waste treatment, is the separation of solids, as well as chemical and biological contaminants transported in liquids. Filtration is a principal means for effecting such separation.
Another growing segment of the market for filtration products is the residential user. News releases about contaminated sources of public and private drinking water supplies and increased public awareness of environmental concerns have led to an increasing consumer demand for filtration devices for improving the quality of residential drinking water. In some areas of the world, unsanitary water supplies are common and permit the introduction of biological vectors that, unless removed from the drinking and cooking water, cause wide-spread illness in the population.
In general, filtration requires that the suspension containing the contaminants be passed through a porous medium that either blocks the passage of particulates or biological vectors larger than the pore size of the medium or that absorbs the chemical contaminants. Thus, the porous medium prevents the continued passage of the contaminants in the fluid flow.
A problem with present filters is that to eliminate certain bacteriological vectors, or particulate contaminants of small size, a filtering membrane must be introduced into the fluid flow that contains porous passages that are smaller than the contaminant that is desired to be excluded from the fluid flow.
As there are generally a greater percentage of larger than smaller sized contaminants, the larger contaminants tend to accumulate and sediment against the finer filtering element and to plug or clog it rapidly, thus shortening its useful life expectancy. A common problem in this art is that the higher the efficiency of the filtering apparatus is in eliminating the smaller and smaller contaminants, the shorter and more costly is its use in the filtering system.